Screening of mannanases in actinomycetes and their potential application in the biobleaching of pine kraft pulps |
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Authors: | M D Montiel J Rodríguez M I Pérez-Leblic M Hernández M E Arias J L Copa-Patiño |
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Institution: | (1) Departamento de Microbiología y Parasitología, Universidad de Alcalá, E-28871 Alcalá de Henares, Spain e-mail: mpcopa@ microb.alcala.es Tel.: +34-9188-54634 Fax: +34-9188-54623, ES |
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Abstract: | Fifty actinomycete strains were screened for the production of mannanase activity during growth in both liquid and solid
media. Streptomyces scabies CECT 3340 and Streptomyces ipomoea CECT 3341 were selected for their ability to produce high levels of mannanase (294.3 U/l and 242.9 U/l, respectively) during
growth in liquid culture. β-Mannosidase (15.3 U/l) and α-galactosidase (7.7 U/l) activities were also detected in culture
filtrate from S. scabies CECT 3340. Highest levels of mannanase activity for S. scabies CECT 3340 were achieved in media containing locust bean gum and asparagine (4.8 U mg−1 protein) whilst in S. ipomoea CECT 3341 greatest activity was detected in media containing locust bean gum and yeast extract (13.2 U mg−1 protein). No carboxymethylcellulase activity was detected. In biobleaching experiments, enzyme treatment, carried out with
mannanase activity produced by S. ipomoea CECT 3341, followed by alkaline extraction of pine kraft pulp resulted in the release of colour (A
465, 0.69) and chromophoric material from the pulp (A
237, 12.9; A
254, 6.9 and A
280, 6.7). The ability of this enzyme complex to improve the bleaching of pine kraft pulps was also shown by a pulp brightness
increase (2.4 units ISO) and a reduction in kappa number (from 21.4 units to 20.1 units) with the absence of variations on
the viscosity values.
Received: 23 February 1999 / Received revision: 1 April 1999 / Accepted: 6 April 1999 |
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